Corresponding parting blades and tools are known in the prior art, for example from WO 2013/132480 A1, wherein the internal coolant channel which runs in the interior of the parting blade parallel to the sides, debouches in the vicinity of a cutting insert which is clamped at one or both ends of such a parting blade. Corresponding parting blades essentially comprise an elongated plate with two plane-parallel sides, an upper and a lower edge face and end faces, wherein receiving slots are provided for clamping of grooving and parting-off cutting inserts typically in the region of the end faces of the parting blade. The edge faces and the end faces run essentially transversely in relation to the parallel side faces and connect these with one another.
A cutting edge of such a cutting insert also running transversely in relation to the side faces of the parting blade is typically somewhat longer than the parting blade is thick (measured as the gap between the parallel side faces), so that when cutting a groove in a rotating workpiece the groove produced in the workpiece by the cutting edge is broader than the parting blade is thick so that the parting blade together with the cutting insert penetrate into the groove produced in the workpiece and so correspondingly deep grooves can be made or workpieces can be grooved with a correspondingly large diameter.
In the last decades the material of corresponding cutting inserts has been continuously developed so that the parting blades fitted with the cutting inserts have a high cutting performance and can cut grooves or part off workpieces correspondingly rapidly. In addition, the continuously developed materials and alloys of the workpieces often make higher and additional demands on the machining tools, in particular the cutting elements. However, use with workpieces which are difficult to cut and increased working speed and cut volume are inevitably associated with higher friction and increased heating of the cutting inserts. Overheating produces a very rapid decline in the performance and durability of the cutting elements or cutting inserts, leading to high wear and consumption of the costly cutting elements.
For this reason, corresponding parting blades which are designed to achieve high cutting performance with the associated cutting inserts are provided with integrated coolant supply systems which make it possible to deliver the coolant effectively to the cutting insert and to the vicinity of the cutting edge even during deep grooving or parting off, so that continuous effective cooling of the cutting insert can be carried out during the entire cutting operation.
For this reason, the coolant channels run in the interior of the parting blades which are already per se very narrow and typically have a thickness (i.e. a gap between their plane-parallel side faces) of less than 10 mm and often of only 3 to 6 mm.
Here, the supply of coolant to the internal coolant channel or the internal coolant channels is expediently best provided through a transverse bore which extends perpendicularly through the side faces and on one side is aligned with a corresponding transfer or delivery opening in the bearing face of a parting blade holder and on the opposite side is closed with the aid of caps or covers or screws since the opposite side of the parting blades to the bearing face is usually exposed and the clamping of the parting blades is normally effected solely using the upper and lower edge faces which for this purpose can have a roof-shaped or trapezoidal contour.
Such blanking covers or screws or corresponding clamping claws which close the side of the transverse bore in the parting blade remote from the delivery opening in the holder, necessarily protrude from the side face of the parting blade and can obstruct the stream of cuttings or the guiding movement of the parting blade past radial projections on a workpiece.